Shift register unit, driving method thereof, gate driver circuit and display device

A shift register unit, a driving method thereof, a gate driver circuit and a display device are provided. The shift register unit includes a first pull-up node control unit, a second pull-up node control unit configured to enable a pull-up node to be at a first level at a pull-down maintenance stage under the control of a first clock signal, a first pull-down node control unit configured to enable a pull-down node to be at a second level at the pull-down maintenance stage under the control of the first clock signal, a second pull-down node control unit, a gate driving signal output unit configured to output a gate driving signal under the control of the pull-up and pull-down nodes, and a carry signal output unit configured to enable a carry signal output end to output a carry signal under the control of the pull-up and pull-down nodes.